Everyone's enjoying confusing group rules, insurance and the law. From a purely legal perspective (unless they've radically changed things and I've missed it) the requirement is that in the last 90 days you've done 3 takeoffs and landings as sole manipulator of the controls. If you haven't done it go out and do them on your own. No problem.
If you are nervous about your currency and want someone with you then you need someone else who will be PIC while you do it because legally you cannot be PIC if he/she is in the a/c with you because you're outside the 90 day rule. (Not too difficult so far?).
If you read your finely crafted ANO you will find nothing in there that prevents you as PIC from teaching your granny to fly, however if she was
flying or about to fly a flying machine or glider for the purpose of becoming qualified for:
(a) the grant of a pilot's licence; or
(b) the inclusion or variation of any rating or qualification in a pilot's licence.
you would need to have an FI rating. (see Art 80) If you hand over the controls to someone else there's nothing to stop you from continuing to be PIC although Art 93 requires "a pilot" to be strapped in at the controls at all times and in an a/c that requires 2 pilots, "2 pilots" during take-off and landing. Note it specifies "a pilot" not "the commander", so you can quite legally be PIC while chatting up the flight attendant in the aft galley so long as the FO is strapped in up front.
Ergo IMHO there would be nothing illegal in me being PIC with no FI rating while one of my fellow group members poled it around the sky. On a practical level, if he felt so insecure that he thought my being there was better than him doing it solo I might demur on the grounds of common sense. He of course would not be able to log the time as a crew member because he wouldn't be qualified so to act.
You all know the privileges of your license, e.g. PPL(A)
(2) The holder may not:
(a) fly such an aeroplane for the purpose of commercial air transport, public transport
or aerial work except in accordance with paragraph (3);
Aerial Work is defined in Art 259. Letting your mate have a pole is not per se Aerial Work.
There is no requirement to log the fact that you've done 3 landings to retain your currency, in fact there's no requirement to log landings at all (see Art 79) you could quite happily go up with another pilot for an hour with you each logging 30 min as PIC and him doing the landing(s). It would however be sensible to record doing them so you have the answer to hand if asked.
If they wanted the person doing the landings to be PIC or Pu/t they would have said so, the fact that they used the terminology "sole manipulator of the controls" is good enough in my book to indicate that that is precisely what they meant.
Final caveat, the fact that something is legal does not mean it's sensible and it doesn't protect you from being done under some other provision, e.g. for endangerment under the Civil Aviation Act.